Low NOX radiant tube burner and method

Claim 1

A radiant tube and burner assembly comprising: (a) a radiant tube having a burner leg and an exhaust leg; (b) a plenum positioned at least in part normal to and between the burner leg and the exhaust leg for mixing combustion air with at least a restricted quantity of products of combustion from the exhaust leg and for directing the resultant mixture into the burner leg; (c) a jet pump positioned upstream of said plenum for directing high velocity combustion air through a nozzle and along a central longitudinal axis of the plenum and for aspirating at least a restricted quantity of the products of combustion; (d) a duct in registry with the plenum and the exhaust leg for directing at least a restricted quantity of the products of combustion to the plenum; (e) a restricted orifice associated with the duct and dimensioned in side in relation to the jet pup nozzle to control the amount of products of combustion aspirated to the plenum; (f) exhaust means associated with the exhaust leg or duct and upstream of the plenum for exhausting the quantity of products of combustion not aspirated by the jet pump; and (g) a fuel source directed into the burner leg for providing fuel to mix with the combustion air and products of combustion; whereby all air intake is vitiated during normal operated and the fuel, combustion air and products of combustion provide a low temperature, uniform flame for reducing NOX emissions and providing uniform radiation along the radiant tube.

Claim 14

A method of reducing NOX formation in a radiant tube and burner assembly comprising: (a) directing a stream of high velocity combustion air from a jet pump axially through an air plenum to avoid swirl; (b) restricting a quantity of products of combustion flowing from an exhaust leg of the radiant tube by an orifice of the radiant tube; (c) aspirating the quantity of products of combustion circulated through the orifice by means of said combustion air; (d) exhausting through an exhaust means of the radiant tube the quantity of the products of combustion not aspirated; (e) mixing the quantity of products of combustion aspirated with said combustion air to form a mixture of from 14% to 18% oxygen and to vitiate all air intake during normal operation; and (f) mixing said mixture with a fuel in the burner leg of a radiant tube and downstream of a flame retention device to cause burning.

Claim 15

A method of reducing NOX formation in a radiant tube and burner assembly comprising: (a) directing a stream of high velocity combustion air from a jet pump axially through an air plenum to avoid swirl; (b) restricting a quantity of products of combustion flowing from an exhaust leg of the radiant tube by an orifice of the radiant tube; (c) aspirating the quantity of products of combustion circulated through the orifice by means of said combustion air; (d) exhausting through an exhaust means of the radiant tube the quantity of the products of combustion not aspirated; (e) mixing the quantity of products of combustion aspirated with said combustion air to form a mixture of from 14% to 18% oxygen and to vitiate all air intake during normal operation; and (f) mixing said mixture with a fuel in the burner leg of a radiant tube and downstream of a flame retention device to cause burning.